1. Field of The Invention
The present invention relates generally to a measuring chip for an optical analyzer. More specifically, the invention relates to a measuring chip for an optical analyzer, which is effectively used to optically analyze a sample by irradiating a sample solution, which is introduced onto a translucent or transparent substrate, with light.
2. Description of the Prior Art
Analytic operation for irradiating a sample solution arranged on a translucent or transparent substrate with light to analyze a sample on the basis of variables, such as the refractive index and absorptivity of reflected light and transmission light, is often carried out. As an example of an examination method utilizing an immune reaction in a clinical examination or the like, there is an optical analyzing method capable of detecting a change of a physiologically active substance with high sensitivity, e.g., an optical analyzing method utilizing the surface plasmon resonance (SPR).
In the case of the optical analyzing method utilizing the surface plasmon resonance, a typical measuring chip for use in an optical analyzer comprises a translucent or transparent substrate, a metal thin film formed thereon, and an immobilizing film, which is formed thereon and to which a physiologically active substance suitable for an object to be analyzed is immobilized. The measuring chip having such a construction is set on a prism of the optical analyzer so that the translucent or transparent substrate faces the prism. A sample solution is continuously fed onto the surface of the immobilizing film by means of a supplying pump, or the liquid surface in a cell for containing a sample solution therein is arranged so as to contact the immobilizing film, so that the physiologically active substance interacts with the object to be analyzed (see, e.g., Japanese Patent Publication No. 5-2181, Japanese Patent Laid-Open No. 63-75542).
As described above, in most conventional optical analyzers, the supplying pump or the sample solution containing cell is used to supply the sample solution to the measuring chip. Therefore, the conventional optical analyzers are large-scale and complicated. In addition, although the quantity of a sample solution required for a single measuring chip for an optical analyzer to measure a sample is very small, it is necessary to prepare a large quantity of sample solution for an analysis. For that reason, the development of a small analyzer having excellent portability has been far behind.
In the case of the optical analyzing method utilizing the surface plasmon resonance, the incident light entering the reverse surface of the translucent or transparent substrate and the reflected light from the metal thin film are optically analyzed to obtain necessary information, and it is sufficient for a very small quantity of sample solution to exist on the metal thin film on the surface of the translucent or transparent substrate. However, in fact, it is required to prepare a large sample volume, so that it takes a lot of time and money to prepare the sample.